Toroidal coil



Jan. 8, 1929. 1,698,650

E. F. PARKS TOROIDAL COIL Filed Aug- 51, 1925 2 SheetS-Sheei l Jan. s, 1929( 1,698,650

E. F. PARKS TOROIDAL C OIL Filed Aug. 31. 1925 2 sheets-sheet 2 Patented Jan. 8, 1929.

UNITED STATES PATENT OFFICE.

EDWARD F. PARKS, OF PROIIDENCE, RHODE ISLAND, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO THE NEW ENGLAND TRUST COMPANY, TRUSTEE, A CORPORATION OF llVIASSACHUSETTS.

TOROIDAL COIL.

Application led lAugust 31, 1925. Serial No. 53,639.

This invention relates to electrical coils and particularly to toroidal or doughnutshaped coils for use with radio apparatus and for other purposes.

One object of the invention is to provide a toroidal or similai'ly shaped coil which is self-sustaining without the use of a core, flanges, disks or other supporting means, and which is capable of resisting considerable strain and stress wit-hout becoming deformed or distorted.

Another object of the invention is to provide a toroidal coil in which the windings of wire or other conductor are disposed to form a skeleton structure and to mutually cooperate to brace and stiften the coil against distortion or disintegration.

Another object of the 'invention is to provide a coil of the type specified in which the windings are disposed and arranged to obtain the maximum electrical effect with a low distributed capacity and minimum high frequency resistance.

'Another object of the invention is to provide a coil of the type speciied which can be produced by machine winding whereby to render it economical to manufacture.

Another object of the invention is to provide a method vof producing a coil of the type specified which can be performed without the use of special formers or complicated apparatus, and without requiring particular skill or expertness on the part of the workman.

Further objects of the invention are set forth in the following specication which describes a preferred form of the coil and a preferred method of producing it, as illustrated bythe accompanying drawings. In the drawings:

Fig. l is a view of one form of coil embodying the invention;

Fig. 2 is a view illustrating the initial arf rangement of the windings of the coil before it is bent or formed into a tore;

Fig. 3 is an end view of the windings of the coil showing a plurality of turns laid one over another; y

Fig. -l is a more or less diagrammatic view illustrating the method of disposing the turns of wire or other conductor in winding the coil; and

Fig. 5 is a similar view illustrating alater stage in the winding of the coil.

The advantages ofthe toroidal or doughnut form of coil for radio telegraphy and telephony are well known to those versed in the art. This type of coil provides a closed magnetic field or, in other Words, the magnetic field of the windings is confined to a predetermined area which prevents undue in'iuence on adjacent circuits, on elements ofthe same circuit, or on adjacent coils. Moreover, it is not readily influenced by outside magnetic lields. In multi-stage radio frequency circuits its use eliminates inductive feed-back, and rejects interference influences from adjacent electrical apparatus or circuits. In radio receiving sets lof the socalled neutrodyne type its use reduces the magnetic linkage so that neutralizing is more readily accomplished without mounting or associating the coils at critical angles. Through its use the selectivity of a set may be greatly increased byeliminating signal energy picked up from nearby stations, and thus distant stations can be worked at wavelengths approximating those of locals with greater freedom from interference. Besides the above mentioned advantages of this type of coil for radio work it may have other applications not herein specilically stated.

The present invention embodies broadly the principle of winding wire or other conductor helically of a straight axis with the turnsor convolutions spaced at a distance apart to provide an openwork or lattice-like structure in which each turn extending in a given direction crosses at an angle a previously wound turn extending in the opposite direction, so that all of the convolutions are tied or bound at the crosses and thus held from lateral displacement to provide a firm, stable mechanical structure of generally cylindrical contour which, after being removed from the winding mandrel, may be shaped or formed into a ring or tore without materially affecting the mutual relationship of the turns; the resultant coil being of true toroidal form, possessing great mechanical strength and stability, and having the turns so disposed as to obtain the maximum electrical etticiency.

As before mentioned, a particular object of the present invention is to provide a toroidal coil of strong and stable structure, and a method of producing the same which lends itself to economical manufacture. To this end I employ any suitable mechanical means for winding the wire or conductor which constitutes the turns or convolutions of the coil, and preferably l wind it on a straight spindle or arbor 2 such as shown in Fig. 4. rThe spindle 2 isrotated and the strand of wire or other conductor fed thereto and guided or traversed longitudinally thereof either by hand er by suitable instrumentalities such as usually providedin winding machines of well known construction. ln feeding the wire 'w to the mandrel or spindle 2 it is guided longitudinally thereef to dispose it in helical convolutions with a space between the adjacent parallel turns. This method of winding, known in the art as universal wind, or

as a cross-wind, is distinguished from an ordinary spool wind in several particulars. Tn the first place, the parallel turns are not contiguous, that is, the wire is not laid in a close spiral as in a spool wind, but is disposed in open helices. Furthermore, the turns of the vfinding in the different layers Abear Va definite relation to each other, and in thepresentexainple each turn in each lay-` er builds up on, or overlies, a corresponding turn ina previously wound layer, this system being known in the art as honeycomb or lattice winding. Such a method of laying on the turns of wire is shown and described in U. S. Letters Patent No. 1,490,040, granted April 8, 1924, tO Morton Vil. Sterns. Either the honeycomb wind, so-called, or a variation thereof, as described in U. S. Letters Patent No. 1,490,041 of even date to the lsaine inventor, may be employed for producing the present improved toroidal coil and a complete understanding of the system will be obtained from the following brief description as applied to Figs. 4 and 5 of the accompanying drawings.

In Fig. 4 the mandrel 2 may represent the winding machine spindle which is rotated by power-operated means not herein shown, and a reciprocating guide is usually einployed for traversing the wire longitudinally of the spindle, although this is not herein shown as in some cases the wire may be guided by hand. Tn starting to wind the coilthe wire 'w is fed to the rotating spindle 2 and traversed thereon from theV point o to point c which define the endsof the windings. As the wire is traversed from Z) to c it is deposited on the mandrel 2 in spiral convolutions or helical turns which are disposed at an angle to the axis of the mandrel. Tn the presentexample of the windingthe winding spindle 2 makes approximately eight revolutions while the wire fw is being traversed from Z) to 0, and consequently there will be eight turns in the length of the coil or, technically, an eight wind. This is an arbitrary selection, however, as the pitch or lead of the wire may be made greater or less in accordance with the diameter on which it is being wound or in proportion to the length of coil to be produced; the prime consideration being to lead the wire at such a pitch as to insure against the Jturns slipping out of place.

As the wire fw reaches the end of the coil at c its direction of tr lead it back to the star-ting point o, a vsharp bend er knuckle being formed where the wire starts back in the opposite direction. As the wiretraverses back in this c irection a second series of reverse turns or helices will be formed with the wire crossing the previously laid turns at a sharp angle on opposite sides of the spindle at the points e, e, etc. Tt will be noted by reference to 4 that the crossing points e ofthe wire advance slightly circinnferentially ofthe spindle 2, rom one end of the coil to the other and back again, this being effected by causing an incrementof motion in its traverse over the speed of rotation of the winding spindle, or in the technique of winding a gain of the with respect to the rotation of the spindle. Statedbriefiy, the traverse of the wire is not in direct ratio to the spindle revolutions, but has a gan thereover which is designed for a purpose as Vlater explained.

As the wire is traversed back, upon reaching the starting point o its direction of feed is again reversedV at the bend or knucklel 7i, as illustrated in Fig. 5. The wire is then traversed back toward the point c again, but instead of being laid on over the first series of turns, it is disposed at one side hereof, and preferably with an appreciable space between the turns. This system is termed an open wind and in the present example the ratio of the traverse to the rotation of the winding spindle is plotted or calculated to produce a definite disposition of each series of turns of the winding in a given lay/*er so that they substantially overlie or fall in the same plane as corresponding turns extending in the same direction in an adjacent under layer'. This system of winding is explained in detail in the patent first above referred to ane while notl essential te the coil of the present invention it is preferable as making for certain electrical advantages. lith the open wind as exemplified in either of the patents to Sterns, the turns of the coil are spaced apart and separated by air gaps whereby to increase the dielectric effect, and particularly to reduce the distributed capacity of the windings as well known in the art.

Referring to Fig. 5, as the wire reaches the point c in its traverse to this end of the coil ence more, it is reversed again at L. At this point it will feed back with the turns spaced apart from the previously laid turns extending in the same direction and he winding continues in this manner until the wire has formed a network of crossing turns with diamond-shaped openings o therebetween, as partially indicated in Fig. 5 and shown more graphically in F i0. 2. This network or latverse is reversed to traverse eoope of {.he invention. The Coil may he bent. to various shapesas eomprehended Within he meaning of *die term toi'oidel, for ilisuiiee, of horseshoe or half ying forni. Therefore., without limiting myself to the exact eiiihodimeii of the inyentioii or to 'the pieoise method o producing the same es herein ee 'lfoith7 l claim:

l. A toi'oidzil coil composed of sexies of bums of Spirally Wound eoiiduetoi having the oenvoluioiis of adjacent eei'iee disposed in divergen planes to cross each other at an angle sufficient to prevent slippage of he tunis Where engaged at the crossings.

2.- A toioidel coil Comprising Several sei-ies of helical turns eizmged with the turns in ezioh series spaced it a. distance ape-.IE and crossing' the turns of en edjeeeii series ai a suiioieiit angle to provide a stable openwoil; siueture. y

3. A toioidnl coil ooiiiprising a plurality of Series of helical eonvohiione of condueoi' Yof helical turn-ss of: coiioueoi' extending in oppoeie direotioue to ei'ofas eeeh ohei' un with the uins of one fries Hubei-:iii-

ovei'lyiig he uiiis ling in the direction in fm undeilying; series and forming e latieelie eti'uotuie having diamond-Shaped openings between the turns,

y In eeiiiiony whereof I affix my sigiizituie.

ETWARD F. PARKS. 

